In the related art, a waterproof connector which connects wires is mounted in an automobile and the like. For example, a connector is known which includes a female connector, which has a cylindrical inner housing in which a cavity capable of accommodating a female terminal is formed and a cylindrical outer housing which surrounds the inner housing, and a male connector, which has a cylindrical male housing in which a cavity capable of accommodating a male terminal is formed. The connector is formed by fitting both the female and the male connectors.
In such a kind of connector, an annular rubber packing is mounted in an outer circumferential surface of the inner housing of the female connector. When the both connectors are fitted with each other, the male housing is inserted into a gap between the inner housing and the outer housing of the female connector, and the packing is brought into close contact with each of the outer circumferential surface of the inner housing and the inner circumferential surface of the male housing. Thus, it is prevented that water is infiltrated into the gap between the cavities.
However, such a kind of waterproof structure has a problem that the outer diameter dimension of the connector is enlarged since a space for mounting the packing is necessary inside the female connector. With regard to this, for example, as a waterproof structure which does not use a packing, a structure is known in which a resin seal plate having an elasticity is provided in an inner surface of the depth side of a female housing, and a cylinder tip of a male housing in a fitting direction abuts on the seal plate of the female housing over the entire circumference which has an annular shape when both connectors are fitted, thereby preventing the infiltration of water (for example, see Patent Literature 1).